Fluid Friction

Q. Birds fly through the air. What force(s) act on the birds?

1. Sliding friction
2. Air drag
3. Gravitational force
4. Static friction

Q. How a polishing (highly) a surface increases friction?

Q. What do you mean by fluid friction? Which factors affect fluid friction?

Q. High speed bullet trains has a streamlined body in order to ___________ .

1. increase friction
2. None of the above
3. make them attractive
4. decrease friction

Q. Friction due to liquids and gases is known as friction.

1. rolling
2. fluid
3. sliding

Q. Increasing surface area ___ air drag on a freely falling object.

1. increases
2. decreases
3. None of the above
4. doesn't affect

Q. What do you mean by fluid friction? Which factors affect fluid friction?

Q. A footballer throws a ball in the air. In air what type of friction is acting on the ball?

1. Sliding friction
2. Rolling friction
3. Static friction
4. Air drag

Q. It is because of air drag that cats don't get hurt on falling from a height.

1. True
2. False

Q.

Friction can be reduced by ___________ .

1. Using ball bearings

2. Polishing

3. Streamlining

4. All of them

Q.

Examples where static friction and fluid friction act at the same time

Q. Increasing surface area ___ air drag on a freely falling object

1. Decreases
2. None of the above
3. Doesn't affect
4. Increases

Q. Select the incorrect statement.
A boat running in water will _______.

1. produce heat
2. face sliding friction
3. face air drag
4. face water drag

Q.

What is the frictional force exerted by fluids on objects moving through them known as?

1. Lift

2. Thrust

3. Drag

4. Weight

Q. It is because of air drag that cats don't get hurt on falling from a height.

1. True
2. False

Q.

Which of the following options depicts the frictional force phenomenon?

1. A boulder rolling down a mountain

2. Airplane flying

3. A swimmer in river

4. None of these

Q.

In which of the following options is frictional force working?

1. A boulder rolling down a mountain

2. Airplane flying

3. A swimmer in river

4. None of these

Q. How does a cat not hurt itself on jumping or falling from a height?

1. It has soft skin which prevents injury.
2. It brings its legs close together such that its weight is evenly distributed when it lands.
3. It uses its tail to save itself.
4. It spreads its legs wide apart and increases air drag.

Q. Imagine that an object is falling through a long straight glass tube held vertical; air has been removed completely from the tube. The object does not touch the walls of the tube. Will the object experience any force of friction?
[2 marks]
[Exemplar]
[Fluid friction]

Q.

Which of the following methods will help in reducing air drag?

1. Using ball bearings

2. Polishing

3. Using lubricants

4. Streamlining

Q. Which of the following is the most efficient method to reduce air drag?

1. 
   Streamlining
2. 
   Lubrication
3. 
   Using ball bearing
4. 
   Polishing

Q. Which of the following is the most efficient method to reduce air drag?

1. 
   Using ball bearing
2. 
   Polishing
3. 
   Streamlining
4. 
   Lubrication

Q. Which of the following is the most efficient method to reduce air drag?

1. 
   Using ball bearing
2. 
   Polishing
3. 
   Streamlining
4. 
   Lubrication

Q. A space shuttle while descending rapidly to the surface of earth from a mission gets heated up intensely and catches fire. Assuming no malfunctioning of its engine or components, what can be a possible cause?

1. Gravitational pull of the Sun is too strong on the shuttle.
2. Earth's atmosphere offers frictional force.
3. Velocity of the shuttle is too low.
4. Parachutes are attached.

Q.

An aeroplane flying in the atmosphere experiences no friction.

1. True

2. False

Q. The frictional force on any object exerted by fluids are called _________

1. normal force
2. magnetic force
3. drag force
4. electrostatic force